Extrusion of food strip products with undulating edges, such as lasagna noodles, is performed by dies which have strip extruding passageways designed to extrude the edge portions of the strips at a greater velocity than the central portions of the strips so that the edges undulate. Generally the greater velocity of the edge portions is produced by contouring the passageways to have reduced resistance to the flow of the dough at the edges of the passageways.
One type of prior art lasagna extrusion passageway has an elongated narrow orifice which includes a rectangular central portion of a first width, end rectangular portions of a second width which is less than the first width, and terminating circular portions of a diameter slightly larger than the second width. The larger central portion of the extrusion passageway extends substantially through the die. Large diameter bores extend from the rear of the die and the edge portions of the extrusion passageway open into these bores to substantially reduce the length of the edge portions of the extrusion passageway. The reduced length of these edge portions results in reduced resistance to flow of the dough to produce the undulation of the edges of the strip of dough as it is extruded. The circular terminating portions of the die slit provide reduced flow resistance to compensate for edge resistance which otherwise could produce tearing or non-uniform flow of the edges of the extruded strip.
Prior art lasagna extrusion dies have their extrusion passageways extending downward in a vertical plane so that the lasagna strips are extruded downward in the vertical plane. The extrusion velocity is relatively slow and the lasagna noodles are severed by a cutting tool moving across the face of the extrusion die.
In the manufacture of salty segmented strip snack products such as snack chips, a higher rate of extrusion, compared to lasagna noodle extrusion, is desirable to make practical quantities of product. At such higher rates of extrusion, cutting the segments by wiping a cutting tool across the face of the die is impractical since the segments are distorted by the cutting tool. Extruding and cutting the strip dough products on a horizontal conveyor avoids the distortion of the snack segments. When horizontal extrusion of edge undulating strips is attempted, the undulations are highly irregular, and randomly spaced.